CVE-2025-31363: Data exfiltration via AI plugin Jira tool

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-04-16 · updated 2026-06-17
Weakness: CWE-1426

Description

Mattermost versions 10.4.x <= 10.4.2, 10.5.x <= 10.5.0, 9.11.x <= 9.11.9 fail to restrict domains the LLM can request to contact upstream which allows an authenticated user to exfiltrate data from an arbitrary server accessible to the victim via performing a prompt injection in the AI plugin's Jira tool.

Affected products

Mattermost: from 9.11.0 before 9.11.10; from 10.4.0 before 10.4.3; 10.5.0 — fixed in 10.4.3, 9.11.10

How to fix

Upgrade to a fixed version: Mattermost 10.4.3, 9.11.10. Check the vendor advisory for mitigations.

References

https://mattermost.com/security-updates

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